Printing is becoming more and more automated. However, the inspection of the final printed results of printing, that is, of the marks made by printing on printed paper, labels, packaging, and so forth, is still mostly manual.
Many different printing workflows are known. Some include making printing plates that are then used in a printing press to place colorant(s) onto a substrate to produce an instance of printed material. Examples of technologies that use printing plates include flexography and offset printing. Other printing processes such as gravure printing use engraved cylinders instead of plates. Some printing workflows print directly from electronic data. Examples include laser printers and inkjet printers.
Many printing workflows include finishing or converting operations following the application of the marks on the substrate. Examples of finishing include the application of a varnish or lacquer, hot or cold metal foil application and embossing. Examples of converting include trimming and die cutting. Unless otherwise indicated or clear from the context, such finishing and converting operations are included within the scope of the terms “printing” and “printing workflow.”
Printing workflows typically include a prepress workflow and a printing stage. The prepress workflow is more and more computerized, and uses, for example, a page description language (PDL), such as PDF by Adobe Systems of San Jose, Calif. USA, or Open XML Paper Specification (also referred to as OpenXPS), an open specification for a PDL and a fixed-document format originally developed by Microsoft Corporation, of Redmond, Wash. as XML Paper Specification (XPS), later standardized by ECMA International as international standard ECMA-388, XML, and many other PDLs useful for describing printed pages.
As defined herein, a printing job may include what herein is called process data: information that defines the production setup and workflow, in terms of the actions (process steps) and software or equipment settings (process parameters) required to produce the printed material. Process data may include one or more files in a job description language, e.g., Job Definition Format (JDF). JDF is a technical standard being developed by the graphic arts industry to facilitate cross-vendor workflow implementation to define process data. A job description language is also called a process language herein.
Note that in general, the approaches described in this BACKGROUND section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, issues identified with respect to one or more approaches should not assume to have been recognized in any prior art on the basis of this section, unless otherwise indicated.